A yeast mutant, PRP20, altered in mRNA metabolism and maintenance of the nuclear structure, is defective in a gene homologous to the human gene RCC1 which is involved in the control of chromosome condensation.
We report on the characterization of the yeast prp20-1 mutant. In this temperature-sensitive mutant, multiple steps of mRNA metabolism are affected. The prp20-1 mutant strain showed alterations in mRNA steady-state levels, defective mRNA splicing and changes in transcription initiation or termination when shifted from the permissive to the non-permissive temperature. In addition, a change in the structure of the nucleus in these cells became apparent. Electron microscopy revealed an altered structure of the nucleoplasm of prp20-1 mutant cells when grown at the non-permissive temperature that was not observed in cells grown at the permissive temperature or in wild-type cells. The wild-type PRP20 gene was isolated and sequenced. The putative PRP20 protein has a molecular weight of 52 kDa. We found that the PRP20 gene is identical to the yeast SRM1 gene (Clark and Sprague 1989). In addition, the PRP20 protein sequence shows significant sequence similarity to the human RCC1 protein (Ohtsubo et al. 1987). This protein has been implicated in the control of chromosome condensation. Based on the phenotype of the prp20-1 mutant and the observed sequence similarity to the human RCC1 protein, we postulate that the yeast PRP20 protein is involved in the control of nuclear organization.
Aebi
M
M
California Institute of Technology, Division of Biology, Pasadena 91125.
Clark
M W
MW
Vijayraghavan
U
U
Abelson
J
J
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000648:ultrastructure; D015825:Chromosomes, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D012326:RNA Splicing; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; C062521:RCC1 protein, human; D012331:RNA, Fungal; D012333:RNA, Messenger; C067050:SRM1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins